Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Patent
1992-06-15
1994-07-26
Cohen, Lee S.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
607 46, 607 58, 607 74, 607139, 607149, 607900, A61N 105, A61N 136
Patent
active
053324013
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the process now known as TCET (transcranial electrotherapy), that is to say the application of a series of electric signals of defined amplitude and duration across the head of a patient or a test animal by means of percutaneous electrodes generally attached to the external part of the ear.
TCET is described in detail in U.S. Pat. No. 4 646 744 issued Mar. 3, 1987. The U.S. patent describes the general concept of TCET and distinguishes it from other known methods, in particular TENS (Trans cutaneous Electrical Nerve Stimulation), electro-acupunture and invasive electrical treatment. TCET is particularly important in the control of chronic refractory pain, but is also important in treatment of addictive states.
We have now found that for TCET to be successful a number of factors must be considered and the application of the electrical signals must be carried out in a precisely defined manner using signals having particular parameters. It is thus the object of the present invention to provide a method of applying TCET which is effective and reproducible.
U.S. Pat. No. 4 646 744 discloses the application of a signal comprising trains of pulses separated from other trains by off periods. Each of these trains comprises a packet of a certain number of individual pulses spaced temporally from other packets by off periods. The pulses are generally either DC or substantially symmetrical AC wave forms applied at a number of different frequencies, typically 10 Hz, 100 Hz, 25-30 Hz, 500 Hz, and 200 Hz. The pulse width, that is to say the duration of a positive pulse from a zero value to a zero value, is typically 0.1 to 0.5 msec, although pulse widths of 1.5 msec are also mentioned. As described, the signals have a current of several mA, and an amperage of less than 100 mA being sufficient.
As stated, the pulses are given in packets of consecutive pulses described as "trains" separated by off periods which can regularly spaced or which can be irregular and typically increasing in duration, e.g. in an arithmetical progression. The typical overall duration of these series of trains is several days.
SUMMARY OF THE INVENTION
We have now established that there are a number of important parameters to supply if the treatment is to be effective and reproducible. In the first place it is important to consider the impedance of the circuit, as controlled by the electrode attachment to the ear. We have now found that conventional patch electrodes, even if relatively small for accurate placement, as advised in the above-mentioned U.S. patent, provide a relatively high impedance, typically 300-600 k.OMEGA., even when used with electrode gel, and also a relatively large capacitance. Similarly, a blunt gold electrode has an impedance of 300-500 k.OMEGA.. I have found that the electrode should be in the form of a generally conical needle point capable of penetrating the epidermis, so as to provide good electrical contact over a very small surface area. A steel needle electrode of this type provides an impedance of about 65-90 k.OMEGA., whale a carbon needle provides an impedance of about 25-35 k.OMEGA.. The point contact also provides a low capacitance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of an electrode assembly;
FIGS. 2 and 3 are plan and side views of the assembly before being folded;
FIG. 4 is a large side view of the electrode carrier of the assembly;
FIGS. 5A and 5B, 6 and 7 show a power supply circuit and signal generator.
DESCRIPTION OF THE INVENTION
The signal can be provided to the electrode with a very low current. It is highly desirable to use an operating current of only a few microamps, typically 10-15 .mu.A e.g. about 10-12 .mu.A. Thus, the operating current should be a factor of 10.sup.-4 times the operating current suggested in the above-mentioned U.S. patent.
The low current signal can be provided by the simple procedure of using a signal generator working at a much higher current and then including in the circuit a defined high imped
REFERENCES:
patent: 3957053 (1976-05-01), Woo
patent: 4319584 (1982-03-01), McCall
Capel Ifor D.
Davey Ronald W.
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